Testing is a major part of the production process for semiconductor devices, such as chips and memory modules, panels of memory modules, and PCBs. The testing stage of the semiconductor device production process identifies faulty devices and possibly entire faulty batches of devices before they reach the marketplace. The testing stage, however, can also become a bottleneck in the production process if performed inefficiently, especially for devices that require time-consuming testing such as Flash Memory Chips or modules containing Flash Memory Chips. Thus, it is important to have a high throughput at the testing stage.
Most semiconductor devices are placed in trays complying with well-known standards set by the standards body such as JEDEC, for subsequent testing, since most production automation equipment is designed to handle such trays automatically. A typical production tester uses a tray stack as input and 2 or more tray stacks as output for Pass, Fail1, Fail2, etc. The automated test system manipulates trays inside the machine as to allow pickup/placements of semiconductor devices from input trays, to be picked up for placement in test sockets, and then subsequently placed in output trays after performing the test. Such machines generally perform sorting, where the tested devices are placed in the top tray of one the Pass, Fail1, Fail2, etc tray stacks. Devices are generally moved from trays to test sockets 1, 2, 4 or 8 at a time. In addition, semiconductor devices are also moved between assembly stations, as well as shipped, in inexpensive plastic trays.
Testing time is of paramount importance and the main constituents include the indexing time, which is the time to move parts to and from the test socket, and the actual test time. The actual test time is independent of the automation. The throughput is a function of how many devices are tested in parallel by the system at any moment in time, and of the indexing time. These conventional automated test systems are generally very expensive. If the devices to be tested can be transferred a tray full at once, between a JEDEC, or a similar production tray, or a shipping tray, and a test tray, and then are left in the test tray to be tested, the cost of the system to the user is reduced considerably since the indexing time is reduced, and therefore the throughput of the system increases. Ultimately customers are paying for throughput.
In view of the foregoing, there is a need for a more efficient semiconductor device testing apparatus that increases the throughput of the testing stage.
Like reference numerals refer to corresponding parts throughout the drawings. It should be appreciated that the drawings are not necessarily drawn to scale and that the relative dimensions of various components in a given figure are also not necessarily drawn to scale.